1. Field of the Invention
This invention relates to a method and apparatus for securing cables into the ground by means of an improved earth anchor. Earth anchors depend upon the weight of the earth above the anchor and the sheer strength of undisturbed soil which lies above extensions of the anchor. The holding strength is dependent upon the size of the anchor, the depth and the amount of undisturbed earth that secures the anchor.
Earth anchors are used for securing guy lines for transmission poles, logging towers and drilling platforms. They may also be used for any other purpose that requires securing an object to the ground.
2. Description of the Prior Art
In earth anchors known in the art, many complex mechanical devices have been used to drive extensions into undisturbed soil. Many do not achieve a high percentage of earth penetration because the extension plates are small. The prior art anchors fail to utilize the side walls of the hole to absorb the reaction to the thrust during insertion of an extension, and as a result require extensive torques which must be applied from the surface.
U.S. Pat. No. 3,778,944 shows an extension which requires rotation of a rod 13. This device produces less than 75% of a surface increase.
U.S. Pat. No. 3,628,337 has small extension members and is therefore limited in strength.
U.S. Pat. Nos. 825,587 and 1,643,769 extend plates by means of gears and a torque rod that extends to the surface. Substantially all of the extension apparatus must remain with the anchor.
U.S. Pat. No. 1,026,402 shows an anchor which requires the extensions to be driven outwardly by means of a wedge driven down.
U.S. Pat. No. 362,774 shows extensions which are driven by a conical wedge pulled upward.
U.S. Pat. No. 2,660,276 is similar to U.S. Pat. No. 3,628,337 and the extensions are small in area.
U.S. Pat. No. 1,994,520 drives the extensions outward by means of vertical impact.
U.S. Pat. No. 1,546,327 depends upon a vertical force to drive the extensions outward.